Exponential replication of object
Thanks to some help from Jaque Luke (see this post here Animation Nodes: How to unzip a list) I found a slightly different solution: I'm using the Object Instancer, which you can now feed in any Object you like, and first compose a list of target positioning vectors. Then I loop over the list length of those vectors and apply the locations to each Object Instance. A Blend file is here:



The starting point takes a few parameters, allowing you to choose what the distances should be, and also on which column to start. Also, you can pick the object from here:



Next, I'm generating the Columns, and also calculate how many rows each column will have:



I feed that into an extra Sub-Loop to generate the Vectors finally for each column:



This however generates a list of a bunch of vectors lists:



To decompose them, I've used the Expression node in this setup:



Now, all I needed to do was to get the length of this list and use it as a number of iterations for the loop. I loop over each list item (each item is a vector, i.e. the new location of the object), and set the vector accordingly:



and the result is: